Browsing by Author "Ho, Tsung-Lin"

Now showing 1 - 3 of 3

Asymmetric design of photonic crystal surface-emitting lasers with low-threshold characteristics
(2013-08-10)
Hung, Chih-Tsang
;
Ho, Tsung-Lin
;
Lu, Tien-Chang
;
光電工程學系
;
Department of Photonics
We present AlGaAs-InGaAs multiquantum wells photonic crystal surface-emitting lasers by using the transfer matrix method and coupled wave method to achieve a low-threshold operation. The extremely low-threshold gain is achieved by adopting an asymmetric cladding layer design to enhance both of the vertical optical confinement factors for the quantum wells and photonic crystal (PC). By modifying the composition of the AlGaAs layer to raise the refractive index in the p-type cladding, optical field distribution will obviously be shifted to the p side. Hence, it results in a significant coupling enhancement between the optical mode profile and the PC layer. The optimized value of the vertically optical confinement factor of the PC layer is 13.94%, and the corresponding threshold gain can be as low as 19.45 cm(-1). (C) 2013 Optical Society of America
Numerical analysis on current and optical confinement of III-nitride vertical-cavity surface-emitting lasers
(2014-04-21)
Lai, Ying-Yu
;
Huang, Shen-Che
;
Ho, Tsung-Lin
;
Lu, Tien-Chang
;
Wang, Shing-Chung
We report on the numerical analysis of the electrical and optical properties of current-injected III-nitride based vertical-cavity surface-emitting lasers (VCSELs) with three types of current confinement schemes: the conventional planar-indium tin oxide (ITO) type, the AlN-buried type without ITO, and the hybrid type. The proposed hybrid structure, which combines an ITO layer and an intracavity AlN aperture, exhibits not only uniform current distribution but also enhanced lateral optical confinement. Thus, the hybrid type design shows remarkably better performance including lower threshold current and series resistance compared with the planar-ITO type and the AlN-buried type. Furthermore, the multi-transverse mode lasing behavior induced by strong index guiding of the AlN aperture is suppressed to single transverse mode operation by reducing the aperture size. Such design provides a powerful solution for the high performance III-N based VCSELs and is also viable by using current state of the art processing techniques. (C) 2014 Optical Society of America
Numerical Analysis on Current and Optical Confinement of III-Nitride Vertical-Cavity Surface-Emitting Lasers
(2014)
Lai, Ying-Yu
;
Lu, Tien-Chang
;
Ho, Tsung-Lin
;
Huang, Shen-Che
;
Wang, Shing-Chung
We report on the numerical analysis of the electrical and optical properties of current-injected III-N based vertical-cavity surface-emitting lasers (VCSELs) with three types of current confinement schemes: the conventional planar-Indium Tin Oxide (ITO) type, the AlN-buried type without ITO, and the hybrid type. The proposed hybrid structure, which combines an ITO layer and an intracavity AlN aperture, exhibits not only a uniform current distribution but also an enhanced lateral optical confinement. Thus, the hybrid type design shows a remarkably better performance including lower threshold current and series resistance compared with the planar-ITO type and the AlN-buried type. Furthermore, the multi-transverse mode lasing behavior induced by strong index guiding of the AlN aperture is suppressed to single transverse mode operation by reducing the aperture size. Such design provides a powerful solution for the high performance III-N based VCSELs and is also viable by using current state of the art processing techniques.